The deity Sia embodies the elements of presence of reason, insight and wisdom as the “General of the Lower Egypt” in the Egyptian mythology.
Ever since the Pyramid Texts, Sia has been associated with Hu, the „General of Upper Egypt” and embodiment of the word. While Hu is primarily bound to the Creator, Sia encompasses a much vaster area, as wisdom and knowledge belong to the general presence of a deity.
Therefore, also other gods can be related to Sia when it comes to bearing witness to their wisdom. This is particularly often the case of the God Thoth, who is the lord of knowledge, with many points of reference no less.
As Thoth gives his speech as a vizier to the Lord of the Heavens in his barque, Sia is standing to his right, holding the Book of Gods (Pyr. 267). Both Gods come thusly together.
Siegfried Schott called Sia and Hu the helper gods of formation of will. In the Greco-Roman period, Sia became a designation of Thoth.
We can thus say that Sia is the personification of knowledge and reason.